Fibromyalgia (FM) is a chronic rheumatic disease of high prevalence and great clinical impact. However, the treatment for FM has limited efficacy, with an effect size of about 0.5. Recent studies have found raised levels of glutamate in the insula, hippocampus and posterior cingulate cortex regions of the brain. This has led a number of authors to suggest the usefulness of glutamate blocking drugs in the treatment of FM.

Aims: To evaluate the efficacy of memantine in the treatment of pain and other symptoms of FM and to assess its efficacy in reducing brain glutamate levels in patients with FM. Material and methods: Randomized controlled trial, of six months duration (including a dose adjustment period of one month). 60 patients with FM will be recruited for inclusion in the study upon fulfillment of selection criteria, and they will be randomized in two groups: A) Treatment group (n=30), will receive 20 mg of memantine o.d ; B) Control group (n=30) will receive placebo. The main objective is to assess the efficacy of memantine in the treatment of pain (pain threshold, pain perception) and other symptoms in fibromyalgia (cognitive state, health status, state of anxiety and depression, quality of life and perceived improvement. Discussion: There is a need for the development of innovative and more effective alternatives for the treatment of FM. This clinical trial will determine whether memantine can be considered as an option in the treatment of FM patients.

It will be measured by sphygmomanometry, a clinical test widely used and very efficient to identify patients with fibromyalgia. Pain perception will be evaluated with the Pain Visual Analogue Scale (VAS pain). It is a horizontal line, 10 cm in length, anchored by word descriptors at each end (no pain and very severe pain)

It will be measured by the Cognition Mini-Exam (MEC).In people under 65 years old, like the population in our study, the threshold that suggests a "probable case" is <27 points. The Spanish version of the questionnaire will be used.

Cognitive state will also be measured by qEEG event-related desynchronization (ERD) at absolute power of upper alpha rhythms in the parieto-occipital region while cognitive tasks are performed.

Patients randomised to this group will receive film-coated placebo tablets (similar to drug tablets.

Active Comparator: Memantine

Drug: Memantine

Patients randomised to this arm will receive memantine 20 mg daily. This dose will be reached following this schema:

1st week: 5 mg daily

2nd week: 10 mg daily

3rd week: 15 mg daily

From 4th week up to 24th week: 20 mg daily

Other Name: Ebixa

Eligibility

Ages Eligible for Study:

18 Years to 65 Years

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

Male or female aged between 18 and 65 years.

Ability to understand Spanish.

Diagnosis of fibromyalgia carried out by a rheumatologist according to the American College of rheumatology criteria (ACR1990).

Ability to read and understand the Patient Information Sheet

Signature of Informed Consent Form.

6 .In the case of women of childbearing age, commitment not to become pregnant during the entire duration of the study.

Exclusion Criteria:

Undergoing drug treatment for fibromyalgia. Patients undergoing treatment for fibromyalgia will stop treatment and perform a washout period of one week. During that week the patient may take, if necessary, analgesic such as paracetamol, ibuprofen and other NSAIDS to minimize the influence of medication on brain imaging.

Currently taking memantine or having taken memantine during the 2 months prior to recruitment.

Clinically significant and active evidence of liver or kidney disease, haematological, respiratory, endocrine or cardiovascular disease or disorders (patients with controlled diabetes and patients with controlled hypertension and complete or incomplete right bundle branch block can be included in the study).

Use of prescription drugs that may cause relevant drug interactions with memantine according to the summary of product characteristics: NMDAR antagonists (amantadine, ketamine, dextromethorphan), L-Dopa, dopamine agonists and cholinergic agonists.

Use of non-permitted concomitant medication during the week prior to the first evaluation visit or when the patient is expected to require treatment (with at least one of the drugs not permitted during the study): antidepressants (duloxetine, venlafaxine, mirtazapine, bupropion, SSRI, etc.), analgesics (pregabalin, gabapentin, opiates, etc.)

Contacts and Locations

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01653457